Prehospital Trauma Life Support (PHTLS) Practice Test

What mechanism explains the impairment of gas exchange in pulmonary contusion?

1. Blood in the alveoli

2. Collapse of the alveoli

3. Compression of the lung tissue

4. Partial occlusion of the bronchi

The correct answer is: Blood in the alveoli

The impairment of gas exchange in pulmonary contusion primarily occurs due to blood in the alveoli. When a pulmonary contusion occurs, it often results from blunt trauma to the chest, causing bleeding into the lung tissue and the alveolar spaces. This accumulation of blood disrupts the normal air-filled alveoli, replacing oxygen with fluid and impairing the transfer of oxygen and carbon dioxide. The presence of blood within the alveoli makes it difficult for oxygen to diffuse into the bloodstream and for carbon dioxide to be removed from it. This leads to hypoxemia (low levels of oxygen in the blood) and can significantly compromise respiratory function, making it a critical concern in patients with pulmonary contusions. In contrast, while the collapse of the alveoli, compression of lung tissue, and partial occlusion of the bronchi can also affect gas exchange, these mechanisms do not predominantly drive the gas exchange impairment seen specifically in pulmonary contusions. Therefore, the correct answer reflects the primary cause of gas exchange disruption in this context.